Make officially valid (6)
I believe the answer is:
ratify
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">make officially valid</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ratify that I've seen before include "Give formal approval to" , "Fit ray (anag.)" , "Sanction" , "Sign or give formal consent" , "Authenticate" .)